Redundant parallel positioning table device

ABSTRACT

A redundant positioning table device with six or fewer degrees of freedom having four modular legs extended from a base to a table, each legs being with three levels and the same types of joints. In one embodiment, the bottom joint is planar and active, the middle joint is prismatic and passive, and the top joint is spherical and passive. In another embodiment, the bottom joint is prismatic and passive, the middle joint is planar and active, and the top joint is spherical and passive. Fewer than six degrees of freedom is achieved by reducing the number of degrees of freedom of designated joints.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISK APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a redundant parallel positioning tabledevice. More specifically, the present invention relates to a redundantparallel positioning table device for a precise positioning of heavyload samples, instrument and/or apparatus, e.g., in the fields and useof diffractometer machines for synchrotron facilities.

2. Description of the Related Art

Positioning systems and devices for the positioning of samples fordifferent purposes have long been known in the prior art.

Some research on new or existent materials are involving synchrotronX-ray tool and Diffractometers (Dm) machines to investigate the physicaland/or chemical properties. To discover the intrinsic molecular and/oratomic structures and its behavior under different environmentalconditions, the measurements in these large (microscopes) machines arebased on diffraction technique. In order to simulate the real or virtualconditions (e.g., pressure, temperature, etc.) for a sample, theadditional instruments and/or apparatus are sometimes necessary. Thesecould weigh several tens or hundreds of kilograms and appreciable size,and the aggregates (sample & instruments/apparatus) must be manipulatedin the right position towards the incoming X-ray beam. A standardexperimental process includes several operations (and/or phases)—fastset ups, alignments, calibrations, go to exactly required position,keeping the pose for relative long time (e.g., hours or days) then, torestart the whole cycle for another investigation. Following these, arequired positioning device should be able to perform both, simple andcomplex motions with enough precision and speed owing at the same timethe power for carrying the relative high load and to maintain it forrelative long time. Especially, it must be able to do spherical motionsaround a fixed arbitrary chosen point, called rotation center C (orpivot point P) regarding the sample center, located at a distance(d_(C)) from the instrument base.

Parallel kinematic (PK) principle has been recently more and moreinvestigated as positioning concept based on some advantages against thestandard serial (stacked) principle. The most common 6dof topologycalled hexapod is derived from GOUGH [V.E.Gough, Contribution todiscussion of papers on research in automobile stability, control andtyre performance Proc. Auto Div. Inst. Mech. Eng, 1956-1957] and STEWART[D. Stewart, A platform with six degrees of freedom, Proc. Institutionof Mechanical Eng.(UK), 1965-1966] works. The GOUGH-STEWART platformmechanism was applied for the first time as motion simulator [C. L.Klaus, Motion manipulator, U.S. Pat. No. 3,295,224, Jan. 3, 1967] andthen latter as tool positioning in machine tools industry [P. C.Sheldon, Six-axis machine tool, U.S. Pat. No. 4,988,244, Jan. 29, 1991].Actual hexapod structures for positioning (e.g., 6-SPS) are fullyparallel kinematic mechanisms (PKM) composed from symmetric structureswith six variable lengths actuators called struts arranged between twoapproximate hexagonal (or, disc) shapes—base and moving platform parts,respectively. The position (and, orientation) of the platform isresulting as a combination of strong coupled motions of linear actuatedtelescopic bars. The benefits are related with the increased payload,precision and dynamics, due to their intrinsic stiffer pyramidalstructure. The distinctive class designed for precision positioning iscalled precision hexapods.

There are several proposed solutions; some of them as availableproducts. However, when intended to be used inside of diffractometers(e.g. Dm5021/I07/DLS, HUBER GmbH Co&KG, DLS-Diamond Light Source,I07-Beam line) they are exhibiting some drawbacks in relation with therequired manipulation (e.g. load: >50 kg, d_(c)=170 mm, repeatability:±2 μm, speed: 3 mm/s) and the available Dm working space (DxA=400×420mm, D-diameter, A-height) parameters: a) the maximum manipulated loadnot enough (for those fulfilling DxA, or dc), b) the rotation centerpoint distance (dc) not inside of DxA (for all caring bigger load) andc) the workspace relative small (for both, above cases). Shortly, thehexapods volume, especially the heights are too big (or, too small)compared with the performances they offer for the allocated Dm space. Inaddition, the mounting surface of the platform for large instruments notalways well prepared (e.g., large aperture, for cable management).

This is because the designers face with: a) the necessity to pack“inside” of the actuation struts (telescopic bars) an appreciable numberof components (e.g., motor, gearhead/harmonic drive, guides, sensors,etc.); b) the shape of the workspace is resulting complex, because ofthe intersected number and size of the actuators; c) the undesireddynamic effects for moving motorized legs, sometimes appreciable,affecting the maximum speed. And the singularities (and, collisions)occurred must be detected and avoided for precision tasks; however,difficult to be done, as is direct related with the numbers of jointsand components. Finally, the simple motions: translation-X,Y,Z (and/orrotations-Rx,Ry,Rz) are difficult to be predicted by non-parallelkinematic expert staff, when simple and fast alignment operations are tobe done in the experimental rooms.

Other architectures have been investigated during the time for precision6dof positioning tasks.

The U.S. Pat. No. 5,301,566 relates to a six degree-of-freedomparallel-(mini)manipulator having three inextensible limbs formanipulating a platform attached via three non-collinear universaljoints and two-degree-of-freedom parallel drivers. By using the minimumnumber of actuated and supporting points, and bidirectional planarmotors an increased workspace, stiffness and accuracy compared withStewart/Gough mechanism have been claimed, beside of other advantagese.g. (direct kinematics, few components, etc.). However, the static anddynamic characteristics are very much depending on the number ofcomponents (three) being one axis symmetric arranged, only.

There are also several proposals for PK mechanisms working aspositioning table devices. PCT publication No. WO2007/055339A1 describesa three-dimensional positioning table (rectangular shape) which has theability to perform high-precision motions, as a result of combinedactions of mainly two separated positioning devices. An elevating (Z)and a table plate (XYRz/PKM) devices are both connected through a planarbearing support plate and three vertical linear guides. The elevationdevice is including a stage system of two guided wedges which in theirrelative motions against a fixed support produced the lifting/down ofthe platform. However, these combined hybrid parallel-serial structurescannot provide whole motion capabilities spectrum (6dof). The Japanesepatent publication No. JP2012-51054A describes a positioning table whichis using three mobile supports, each of them providing a lifting/downmotion through a combination of three linear guided parts on which onone, the motor is attached; and, on the second a spherical bearing. Aload in space (3dof) is positioned with this tripod architecture throughseveral moving parts and guiding means supposing to affect the generalstiffness.

Redundancy is a relative new concept applied to parallel kinematicmechanisms. It increases the mechanisms capabilities of stiffness,working space, accuracy and speed for both, spatial and planarstructures. Two concepts have been studied until now—the kinematicredundancy (adding a chain/leg) and the actuation redundancy (adding anactive joint), respectively. The redundancy has also the advantage ofavoiding singularities and to work in difficult conditions when one ormore actuators are falling. However, few manipulation and/or positioningproducts have been released until now.

The Japanese patent publication No. JP2010-264526A relates to aredundant spatial parallel mechanism using four pairs of two actuatorshaving one dof each. The architecture is similar with hexapod ones basedon strut actuators but with special designed interconnected joints atthe top end. In order to perform the required motion task, the controlfunction must take into account only six suitable selected activestruts. The resulting height (high) of the device related upon theactuators lengths is similar as in the hexapods case one.

The French patent application No. FR2965207A1 describes a redundantparallel robot having six degrees of freedom. The mechanism can be seenas comprising four articulated kinematic closed chains each with two dofactuation from the base. A main serial chain is supported from otherthrough a rotational joint and then it is connected to the platformthrough separated rotational joints including a pivotal one. The pairsof actuators are located alongside of a quadrilateral shape moving theplatform and acting around the corners. The parallel type singularitiesare avoided. And, by using rotational motors and arms (bars) highworkspaces and dexterity manipulation tasks could be delivered, but nottogether with precision because the stiffness is not at its best.Improved values perhaps are obtained in the embodiment using verticallinear actuators (FR2964337A1), but the platform size is still supposedto be much smaller than the base is.

The Chinese patent No. CN1730235A relates to a redundant parallelmechanism with six degrees of freedom used as a structure for machinetool in order to increase its axial rigidity and workspace, by usingfour telescopic legs, each of them moving around a ring base throughrevolving pairs as part of their sliding blocks. The circular guidesrealize a large range of rotational movement and increase the attitudespace, but the active joints are interposed between passive onesdiminishing the maximum stiffness.

All these devices described above have the capability to partially (lessthan 6 degrees of freedom) or fully (6 degrees of freedom) pose a bodyin space using either non-redundant (e.g., parallel or hybrid) orredundant (e.g., parallel) structures. However, none of the abovedevices is perfectly suitable for specific synchrotron relateddiffractometer applications.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a 6 or fewer degrees of freedompositioning device with superior performance and capabilities by beingmore adapted to the scope compared with devices of the current art.

An object of the present invention is to provide a positioning tablewith an increased size (including the aperture) and adequate shape(flat) supporting and fixing surface for carry the specificdiffractometers loads. Another object is to provide a table which canaccommodate the most demanding tight space requirements by being morecompact (e.g., having a lower profile). Another object is to provide apositioning table with increased precision, including stability. Anotherobject is to provide a device with increased speed. Another object is toprovide a method to intuitively perform simple Cartesian motions (e.g.,translations and/or rotations) automatically or manually.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and object of the presentinvention, reference is made to the accompanying drawings, wherein:

FIG. 1 represents the 6-4-213 topological concept of the redundantparallel positioning table device;

FIG. 2 is the representation of FIG. 1 modified for a 123 redundantparallel positioning table device;

FIG. 3 represents the 6-4-(P1)₂XS general kinematic model for redundantparallel positioning table device;

FIG. 4 is the representation of FIG. 3 modified for a 123 redundantparallel positioning table device;

FIG. 5 represents the kinematic model of 6-4-(2P)PS mechanism forredundant parallel positioning table device;

FIG. 6 is the representation of FIG. 5 modified for a 123 redundantparallel positioning table device;

FIG. 7 is a 3D view of the redundant parallel positioning table devicedesign concept;

FIG. 8 is the representation of FIG. 7 modified for a 123 redundantparallel positioning table device;

FIG. 9 is an example of a Positioning module (Pm);

FIG. 10 is the representation of FIG. 9 modified for a 123 redundantparallel positioning table device;

FIG. 11 is an embodiment of the positioning table device using fouridentical positioning modules;

FIG. 12 is another embodiment of the positioning table device using fouridentical positioning modules;

FIG. 13 shows linear motion of the table along the X axis;

FIG. 14 shows rotational motion of the table around the X axis;

FIG. 15 shows linear motion of the table along the Y axis;

FIG. 16 shows rotational motion of the table around the Y axis;

FIG. 17 shows rotational motion of the table around the Z axis; and

FIG. 18 shows linear motion of the table along the Z axis.

DETAILED DESCRIPTION OF THE INVENTION

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 16/545,382, which is a continuation-in-part of U.S.patent application Ser. No. 15/100,828, which is a national stageapplication of PCT application No. PCT/EP2014/076795, all of which arehereby incorporated by reference in their entireties, on which thisapplication is based.

The inventor of the present invention has surprisingly found that thedevices according to the following aspects of the present inventionprovide a solution to the above described objects of the presentinvention and additionally provide technical effects and advantageswhich were unexpected and surprising in view of the prior art. Thesetechnical effects and advantages will be explained and are apparent fromthe examples accompanying this disclosure.

In a first aspect, there is provided a parallel positioning table device(Rd-PPT) comprising a stationary base (B) and a moveable table (T). Theparallel positioning table device can be a redundant parallelpositioning device table. The moveable table can be moved relative tothe stationary base in all six-degrees-of-freedom (6dof). The moveabletable can have a fixing surface (Σ_(T)). The fixing service can be afixing surface whereupon a sample (Sp) or related bodies (Bo) forinvestigations can be mounted on. At least one set of four supportinglegs may be symmetrically and in pairs arranged around a center of thebase connected with one end to the stationary base and with another endto the movable table. One of the supporting legs can be redundant. Allof the supporting legs can be 213 kinematics chains (K). Within thecontext of the present disclosure, redundant refers to any positioningtable device having at least one set of four supporting legs, wherein atleast one supporting leg is redundant in view of the other legs.

In a preferred implementation of the present invention, the parallelpositioning table device can be modular. Within the context of thepresent disclosure, modular means that the table device comprises thestationary base, the moveable table and the supporting legs in a modularmanner. The supporting legs can be provided as positioning modules (Pm).The positioning modules can be arranged vertically and parallel withrespect to one axis of symmetry (Z) and orthogonal with respect to asecond axis of symmetry (X/Y), preferably as active 2dof pillars.

Each of the positioning modules can be a stacked combination of oneactive Ac—planar driven and two non-active, El—inclined elevation andGu—spherical guiding positioning units (Pu), from which the first two(Ac, El) can be compact parallelepiped blocks with the same base shapeand size.

Additionally, an active positioning unit Ac can be a 2dof in-parallelactuation A unit. The actuation (A) unit may comprise four orthogonalmotion axes, wherein along two of them—adjacent ones, are acting a setof two linear actuation main parts (A11, A12), another (A′11, A′12)being redundant, perpendicularly on the sides of a common mover (M) withplanar guiding surface (Σ₁).

In a preferred implementation, the parallel positioning table device'selevation positioning unit (El) can comprise a pair of parallel wedges(W) with V-type adjustable inclined guiding surfaces (Σ₂₁, Σ₂₂). Thelower part (W1) of the guiding surfaces (Σ₂₁, Σ₂₂) may be fixed on theactuation (A) and the upper part (W2) may be supporting the spherical(S) positioning units, forming a V-type shape with the opposite leg of a(El) positioning unit.

A guiding positioning unit (Gu) may be a compact spherical joint (S).The compact spherical joint (S) can have convex-concave spherical shapesin contact with adjustable (Σ₃₁, Σ₃₂) surfaces. A first part can be atruncated conical pillar p with a precision calibration sphere (S) atone end. Another perpendicularly mounted on the upper side of theelevation (Pu) housing the interconnected (H1, H2) parts integrated inthe bottom side of the table.

In a preferred implementation, all four planar 2P joints may be mountedin pairs (2×2P) on the stationary base having orthogonal axis each other(P1P3/P2P4) and substantially parallel to the stationary base surface(SB) forming a coplanar actuation module (Am), as part of a 6-4-(2P)PSparallel kinematic mechanism, with only linear and spherical joints,respectively and passive joints (P) being all inclined with the sameangle (α).

The positioning modules (Pm) can be located in the middle sides, or inthe corners of a stationary base square and/or movable table in terms ofa central aperture (D).

In another aspect of the invention there is provided a use of theredundant parallel positioning table according to the first aspect ofthe disclosure to generate simple Cartesian spatial: translations—TX orTY or TZ and rotations—RX or RY or RZ motions and linear—X or Y or Z andangular—aX or aY or aZ displacements, as direct involvement of motionswith equal, or equivalent displacements, by using all or only some ofthe corresponding active axes linear motions (tx, ty) and displacements(X, Y).

In a third aspect the present invention relates to a redundant parallelpositioning table device. The redundant parallel positioning tabledevice may comprise a stationary base and a moveable table. The moveabletable may be moved relative to the stationary base in allsix-degrees-of-freedom. The movable table may have a fixing surface uponwhich a sample or related instruments for investigations can be mountedon. Preferably, at least one set of four supporting legs aresymmetrically arranged around a center of the base connected with oneend to the base and other end to the movable table.

Ideally, the table positioning device may be conceived to be modular andhas the supporting legs as positioning modules vertically in-parallelarranged in respect with one axis of symmetry and orthogonal in-pairs inrespect with other of their axis of symmetry.

Each of the positioning modules may be a pre-determinate combination ofone active and two non-active positioning units.

The table positioning device may additionally comprise two degrees offreedom in-parallel actuation components with at least two orthogonalmotion axis each and a planar guiding surface.

In a preferred implementation, the table positioning device additionallycomprises an elevation component based on an inclined guiding surface ofwhich the first said bottom part is fixed on the actuation and thesecond part said upper is supporting the guiding unit forming a V-typeshape with the opposite component from a pair.

The table positioning device may additionally comprise a guidingcomponent with a convex-concave surface connecting the upper side of theelevation component with the bottom side of the table.

All of the active positioning units may be mounted on a planar base andin-pairs, being orthogonal each other and both substantially parallelwith the base surface.

On each of the elevation units may be perpendicularly mounted guidingpositioning units able to permit orientation motions and displacementsfor the positioning modules and by their combined work, the entire tabledevice to be translated and/or oriented.

However, by choosing only part of actuation axis, a positioning devicewith fewer than 6dof can also be made.

In a fourth aspect of the present invention there is provided a basicmethodology for generating spatial motions and displacements ascombination sequences of all or some of the active translational motionsand/or displacements generated by the table positioning device accordingto the third aspect of the present invention.

The invention will now be further illustrated by way of workingexamples. It is to be understood that these working examples will notlimit the scope of the protection of the present invention and areintended and presented for illustrative purposes only.

The followings notations are being used:

Type Kinematics/Geometry A_(i), A Guiding, center platform points B_(i),B_(i0) Actuation, fixed base points C_(i), C, Sliding points, rotationcenter a_(i), b_(i) Guiding, actuation points distance q_(i) Generalized(actuated) coordinates J Joint Dof, dof, (f) Degrees-of-freedom (joints)K Kinematic chain P, (Pl)₂, S Prismatic, planar (2dof), Spherical JointsR (Rx, Ry, Rz) Rotational motion T (XYZ) Translational motion(Displacement) (Σ), (C) Surface, curve d Distance l Links I, . . . , IVKinematic levels 1, 2 , 3, 4 Actuated joints motion i, j = 1, . . . , 4Index (number of points, chains, etc.)

Type Design/Drawings Ac, (A) Actuators B, (Bo) Base, body (e.g.,instrument) El Elevation unit F Fixing means (e.g., screw) Gu, g Guidingunit, means H Housing L, l Lengths M (m) Mover (motor) Pm (Pu)Positioning module (unit) P Pillar r, D Radius, diameter S, s Spherical(joint), Sphere Sp Sample T Table W Wedge α, β, γ, ψ, φ, θ Angle/angularmotion (displacements) ⊥, ∥ Perpendicular, parallel (ax)

The architecture of a positioning device is an important factorregarding its capabilities. The chosen structure, kinematics, geometry,and optimum design affect the required final static, kinematic anddynamic parameters.

The graphical representation of a structure working as a positioningtable device is proposed in FIG. 1. The topological kinematic concept isfundamentally based on two rigid bodies (or, elements)—a first element(1) called the base (B), generally fixed to the ground, and the secondelement (2) supposed to move called platform, or table (T). Both of themare connected by four identical kinematic chains or, legs (K_(i)), i=1,. . . , 4—a succession of mobile rigid pairs of links (l_(i.1), l_(i.2))and triplets of joints (J_(i.j)) arranged on three levels in the samesuccession regarding joints' dof (f_(ij)=213) starting from the primaryelement (1). All joints at the first level (I) situated on the base arecalled actuated or active joints. (J _(iI)) are actuated (bold andunderlined noted), whereas the remaining joints situated on levels two(II) and three (III) are non-actuated or passive joints (J_(iII),J_(iIII)). By this symmetric structural arrangement, the total degreesof freedom or mobility (M) of the mechanism computed withKuzbach-Grübler formula: M=6n−Σ_(i) ^(j)(6−fi) for spatial mechanisms isresulting as six (M=6), because moving parts n=9, number of joints j=12and their degrees of freedom f_(i)=2, 1 and 3, (j=1 . . . 4, 5 . . . 8,9 . . . 12). The result qualifies the kinematic mechanism (6-4-213) ashaving full spatial mobility, however, obtained with the price ofredundancy. The degree of redundancy comes from one chain addition(Rd_(K)=1) and the actuators number (Rd_(A)=2). In fact, the above graphrepresents not only one type of the mechanism's topology, but an entireQUATTROPOD's (QP) 6dof redundant PM family. Each member depends onparticular choice of joints, e.g., 1-P (Prismatic), 2-PR (R-Rotation)3-S(Spherical). These particular very symmetric, over actuated, andover-constrained members are able to perform heavy load stable motionswith increased static and dynamic capabilities because of supplementarycontact/acting points and power compared with three legs (a tripod),being at the same time more versatile than six points (hexapod)structures.

A general kinematic model helps to define a particular mechanism basedon the actual existing (or developed) portfolio of kinematic joints andtheir general reciprocal arrangements. It is useful also to formulatethe methodology of establishing the input/output (closure) equations.The above 6-4-213 graph permits to freely choose the actuated andnon-actuated type of joints as: 1dof as linear (P), rotation (R), orhelicoidal (H); 2dof as (PP), (PR), or (RR); and 3dof as spherical (S),(UR), or (RRR) joints. A couple of active 2dof joints based onsurface/mover principle could be used having—planar (Σ_(P)), spherical(Σ_(S)), cylindrical (Σ_(C)), or toroidal (Σ_(T)) fixed surfaces, onwhich the linear or curvilinear pathways motions (1, . . . , 8) of thesliders are moving accordingly, as shown in FIG. 3, representing 2P,2R_(S), PR, and 2R_(T) driving joints. Through their simultaneously orseparated combined actions, each of the surface movers (m₁, . . . , m₄)or acting points B_(i) (X_(Bi), Y_(Bi), Z_(Bi), i=1, . . . , 4) definedby pairs of mechanisms' curvilinear generalized coordinates (q _(i), q_(i+1), i=1, . . . , 4 are changing the spherical joints (S) centerA_(i) (X_(i), Y_(i), Z_(i), i=1, . . . , 4) positions, which in turn,moves the attached sample (Sp) and instrument body (Bo) generally inthree spatial translational and/or rotational directions (3T/3R). Inother words, A_(i) points are moving on curves (C_(i)), i=1, . . . , 4each having 2dof (l_(i)—curvilinear coordinate variable, see also FIG.5). Following this, the resultant pose—positions (XYZ) and orientation(ψ, φ, θ) values, respectively, of manipulated objects depends on a) theactuation displacements (q ₁, i=1, . . . , 8) and b) geometrical (a_(i),b_(i), l_(i), d_(i), L, l, R, r) parameter values for a general case ofa 6-4-(Pl)₂XS mechanisms (X—undefined 1dof, (Pl)₂—generalizedcurvilinear planar 2dof joints). Compact Spherical (S) joints are givena simplification in to formulate and solve the motion (position)equation. In this context, the (C_(i)) and A_(i) are called guidingcurves and guided points, respectively. The closure equations can beeasy derived by expressing their coordinates in both Cartesiansystems—fixed (B-XYZ) and mobile (A-xyz); the input (or, output)parameters (X, Y, Z, ψ, φ, θ and q_(i)) are implicitly included.

A kinematics scheme helps to understand the working behavior of amechanism and to formulate the motion equations. The positioning relatedproblems (direct/inverse) are then solved based on the input/outputdisplacements and geometric parameters. A parallel mechanisms kinematicsfor a positioning table based on above 6-4-(Pl)₂XS model is representedin FIG. 5. It is consisting of a symmetric arrangement in-pairs of fouridentical (Pl)₂XS, open kinematic chains, each comprising one planaractuated joint (2P) and two-prismatic (P) and spherical (S) non-actuatedjoints linking a quadrilateral platform-like table (T) with the base (B)of the same shape. The (2P) joints provide 2 dof in a plane located onsubstantially a planar base surface (SB). Each of the opposite actuatedjoints (2P₁, 2P₃/2P₂, 2P₄) being symmetrically arranged, have all theirlinear motion axis orthogonally to each other (e.g., P₁₁⊥P₁₂, etc.) andsubsequently orthogonally with other joints axis (P ₁₁⊥P ₂₂⊥P ₃₃⊥P ₄₄)This symmetric combination of actuated axis forms a general 4×2P planarActuation module (A _(m)), providing a simple and direct way for movingthe table along each of the horizontal Cartesian planar axes—X(X ₁, X ₂,X ₃, X ₄) and Y(Y ₁, Y ₂, Y ₃, Y ₄), respectively. Non-actuated oppositeprismatic joints pairs (P13P₃₃/P₂₃P₄₃) all have identical inclinedangles (α_(i), i=1, . . . , 4) with respect to one of the actuated axis.By the two sets of in-pair actuators motion through simultaneously andconcurrent displacements, the platform moves in an orthogonal direction(Z) to the previously ones (X and Y) based on a V-type kinematicsprinciple. The inclined angles can be any from 0 to n (except π/2)radians; in figure α<π/2. By simultaneously and motions of pairs ofactuated joints in the directions not related to the axis of rotation,or in other words, orthogonally on rotation axis location, the result isthe rotations around one of the planar orthogonal axis (e.g. −X ₁, X₃/Ry); the same procedure applied for Rx(−Y ₂, Y ₄). The thirdrotational motion (Rz) is obtained by the action of all four (2P) jointsin the same direction of rotation (and at the same time)—e.g., Rz/(−X ₁,Y ₁/−X ₂, Y ₂/X ₃, −Y ₃/X ₄, −Y ₄). Through this specific arrangement6-4-(Pl)₂PS (or, 6-4-(2P)PS), a device can do some of the simpletranslational or rotational motions along or around tri-orthogonaldirections very easily and intuitively through decoupled motor motions,which greatly simplifies its control. As is fundamentally statedeverywhere, the minimum number of points to position a body in space isthree, however in this over-constrained, but over-actuated parallelmechanism, the fourth actuator is acting as a means for increasing thekinematics (speed/acceleration) and/or dynamic (inertia) capabilities,beside of an evident fundamental static stability.

Moreover, if damage occurs somehow in a motion axis, the remaining onescould support the work until repaired. Note: The entire kinematics ofthe mechanism is built on using two types—linear and spherical joints,only. This small diversity could reduce the total manufacturing costs.

A good way to materialize the kinematic principle is a key factor tofulfill the required static, kinematic and/or dynamic performances. InFIG. 7, a general design concept is proposed based on 6-4-(2P)PSmechanism kinematic model. Redundant Parallel Positioning Table (Rd-PPT)design consists of a set of four active Positioning Modules (Pm_(i),i=1, . . . , 4) arranged on a substantially planar base surface (Σ_(B))and supporting a platform-like table (T) both having polygonal(quadrilateral) shapes. Each of the Positioning Modules (Pm) comprisestwo types of Positioning units (Pu_(i), i=1, 2) in respect with theirparticipation at the general motion; the first ones are called actuatedand the second ones non-actuated (passive). The Actuation (Ac_(i)), i=1,. . . , 4 Pu are driving means providing 2dof planar motion activated byany of the actual or further developed linear bidirectional motorizeddrivers, as direct driven (DD), e.g., planar motors, coming from each orcombination of stepping, servo, magnetically or piezo effects, orincluding in-parallel or serial or hybrid(parallel-serial/serial-parallel) electromechanical actuationprinciples, or standard (motor-gearhead-motion screw-guides) solution.The last one, in the case of an XY stage provides high stability ofmotion over time, however, not very much to be preferred, because ofcable management difficulties and the resulted reciprocal errors (e.g.,perpendicularity, etc.) with the direct effect on precision. (Note: DDmeans driving the load directly without any transmission mechanism, suchas pulleys, timing belts, ball screws and gears enabling both,high-precision and high-speed positioning. For long strokes, they haveto rely on advanced servo technology to ensure high stability.)

The second types of Pu include the Elevation (El) and Guiding (Gu)means, respectively.

The (El_(i)) units are based on planar wedge motion principle consistingof two—lower, fixed on (Ac_(i)) and upper, supporting (Gu_(i)) partshaving reciprocal inclined planar surfaces of motion and auxiliaryguiding means (g_(i)). By their relative motion and following the resultof the combined actuated unit(s) motions, the upper part moves up anddown constrained by the distance of two opposite (Pm_(i)). For heavyloads and precision motions, the simple way of materializing them is tohave flat sliding surfaces. However, others contact surfaces, asrolling/rolled (rails) or fluid (air, liquid) based principles can bealso taken into consideration if fit with the final requiredperformances.

The Guiding (Gu_(i)) Pu are based on spherical motion principles andconsist at least two parts—lower, fixed on upper part of (El_(i)) andupper, supporting and giving the opportunity the table (T) to beoriented in 3D. The relative motion of the above parts involves aspherical guiding surface in order for the table (T) to perform therequired rotational motions. The type can be any from compact—rolling,sliding spherical joints (S) principle or even separated—simplerotations joints (RRR) and combination of them (UR/RU) design. Otherfunctional principle, as air or any fluid can be also taken intoconsideration depending on the applications.

The optimum design including the size and type of components areaffecting not only the final performances but the entire characteristicsand life of the device. In FIGS. 9, 11, and 12, a Positioning module(Pm) embodiment and two particular arrangements for whole devices areshown. The (Pm) is based on a stacked combination of three basicPositioning units (Pu_(i), i=1, 2, 3): a) first one(Pu_(i))—active/actuated (A) and b) second (Pu₂) and third (Pu₃)inactive (passive)—wedge (W) and Spherical Joint (S) types,respectively.

The (A) Pu is based on in-parallel actuation principle, consisting of inprinciple a square shape base (b) on which a pair of two similar linearactuation units (A ₁₁, A ₁₂) having each of the motion axis (t ₁, t ₂)orthogonal each other is moving in principle a rectangular mover (M)solidary being with a table (t) of the in principle same shape with (b)and fixed through several (at least four) fixing (f₁,) and centered(e.g., pin, at least one) means. In addition, the (t) has in principle aflat surface supporting the next Pu (W). Each of the single actuationunits (A ₁₁) and (A₁₂) is comprised preferably of a linear actuatedmotor (m₁₁), and (m₁₂) with a part fixed on the base and other (pusher)moving free and having a perpendicular and coplanar guide assembly (g₁,g₂) at one end with one part (preferable, the rail) fixed on (M). Bypushing (or, pulling) the (A ₁₁) or (A ₁₂), the (M) is forced to move inand along each of the orthogonal directions (t ₁₁ or t ₁₂), but morespecific in a (general) planar motion (td through their combined action.This orthogonal actuation unit (A) could be developed further, byenforcing its power through the addition of another preferablyorthogonal actuation unit A′ (A′₁₁, A′₁₂). By this, each of the simplemain actuation units are working in tandem with the additional ones (A₁₁, A′₁₁/A ₁₂, A′₁₂) to perform heavy duty motion cycles by the fullworking of all four (4) actuators or helping as partial work, in thecase of working only three (3), for example. This complete new actuationunit (A, A′) is fitting even better with the square base (b) and table(t) shape forming a strong and compact well balanced powered unit, ifnecessary. There is no particular limitation in the specific uses ofseveral other in-parallel linear actuators number, as for example three,five, etc., and the corresponding base/table polygonal shapeaccordingly. However, the two is the minimum. In principle, the guidingmeans (g₁₁, g₁₂) is preferably from sliding principle, but could be anyother, e.g., rolling, magnetic, etc., as well. This at the basein-parallel actuation solution, beside the advantage of being able toprovide no moving cable solution with direct effect on increasedprecision may use specific heavy load guiding means for the mover (M),e.g., 2dof planar bearings Mi. And, in the case of more than twoactuators is opening the way to choose smaller size motors andcomponents for a more compact low-profile actuation module inside of thesame power parameters as two units. In all cases sensors may be used formore accurate motion.

The Put unit consists of a wedge (W) assembly—a fixed lower part (W₂₁)and movable upper part (W₂₂) which in principle, is having the samesupport shape surface as similar to that of the table (t) A unit.

By the relative motion of this pair, through the specific guiding means(g₂₁, g₂₂) with V groove profile surfaces (Σ₂₁, Σ₂₂), the upper part canbe precisely adjusted for smooth and accurate motion against lower onethrough a flexible nervure (n) sliced along one of the sliding guides(g₂₁, g₂₂) and fixed then with several (at least two) fixing means(f′₂), e.g., screws. The (g₂₁, g₂₂) guides could have any another formwhich fit the scope, e.g., angular or even other means for performingthe translational resulted motion (√{square root over (t)}₂), based onrolling principle, e.g., balls, cross-roller rails and carriages; or,for more precise motion requirements, the air guides.

The Pu₃ is the Spherical joint (S) positioning unit preferablycomprising a sphere (s), e.g., calibration ball manufactured formetrological purpose with small roundness errors encapsulated (but,moving) in two houses (H₁, H₂) with reciprocal concave surfaces (Σ₃₁,Σ₃₂), and supported by a truncated conic pillar (p). (Hd is holding (H₂)and it has an external guiding surface (g) for precise and smoothassembly with the table (T) using several (at least four) screws fixingmeans (f₃). The (H₁) and (H₂) are adjustable to permit the smoothrotation of the convex-concave spheres with the center substantiallycoaxial; the conical pillar support axis is perpendicularly mounted inprinciple on the planar support surface of upper wedge (W₂₂). Betweenthe relative motions of the three surfaces the sliding contact principleis preferable to exist.

Two preferred embodiments using above (Pm_(i)) as parts of entireparallel table positioning device assemblies are shown in FIGS. 11 and12. The embodiments consist in using the preferably identical fourmodules (Pm) from above coupled in pairs (Pm₁, Pm₃/Pm₂, Pm₄) being in acircumferential and equidistant way arranged around a common verticalaxis of symmetry of both, the base and table with the same square shapessize (a=b). The actuation/supporting legs axis of symmetry areintersecting a) the middle-points, FIG. 11 and b) the corners, FIG. 12of the actuation (b)/supporting (a) square, respectively. The rigid base(B) in both cases is expected to be a flat surface (plate) attacheddirect to a more generally flat surface of the machine basic structure(diffractometer); or, through additional device (e.g., gonio stages).Note, the base and the flat table could have also various planarpolygonal shapes beside the square one, e.g., octagonal. In bothembodiments, preferably the spherical joints are fixed in the tablethrough partially through holes (h_(i)) machined in the lower tablesurface and the precision manufactured guiding surfaces (g₃) throughscrews. The working diagram of obtaining simple motions, e.g., X and Ytranslations are the same, in both variants. But for the remaining, theyare as the followings: 1) Z motion is coming as—a) four (4) and b) eight(8) and 2) Rx and Ry—a) two (2) and b) eight (8) axes together work(FIG. 11) with direct influence on positioning parameters andsubsequently, the performances. In addition, the distance (d) betweenmodules are different: a) d_(a) and b) d_(b) (d_(a)<d_(b)),respectively. This means the device in the b) case can be designed witha smaller footprint (compact) or with a larger central aperture (D) forthe same footprint for easier cable management as is very oftennecessary in the diffractometers' environment. By the above design both,the (Pm) component and whole assembly, the parallel positioning table isexhibiting a high degree of modularization and re-configurability; and,with an acceptable cost-effective product because relative few andsimple parts are involved.

The way of producing the output motions based on the afferent inputmotions (or, displacements) is a necessary step to understand theworking behavior and to evaluate the capabilities of a new device. Themethod of basic operational principle is described in FIGS. 13-18. TheRd-PPT device is supposed to be with direct drive (planar motors) in thenominal position (Pn). This means null orientation (Rx=Ry=Rz=0) anddisplacements for the table center (A; X=Y=0, Z=h) which iscorresponding null displacements in the actuation units Ac _(i) (B_(i);X ₁=Y ₁₌₀; X ₂=Y ₂=0; X ₃=Y ₃=0, X ₄=Y ₄=0). The basic motion sequences:a) X, Y, or Rz and b) Rx, Ry and Z imposed to the table are seen inrelation with the Actuation modules (Ac _(i)) changes. The finalposition (Pf) is marked as dash-dot line.

Back and forth translational motions along X axis (Tx) are realized bysynchronized motion of all actuators along specified axis and in thesame direction (t_(i1), i=1, . . . , 4); the remaining motions-along Yaxis (t_(i2), i=1, . . . , 4) being inactivated (or free), FIG. 13.Supposing a positive displacement (X) of point (A) from initial to final(A′) position, all the motors related with the same axis must beactivated and in the same direction moving with the same values(X=X1=X2=X3=X4); or at least three of them (the fourth could beinactivated on this direction). For example, if Ac1(X1), Ac2(X2) andAc3(X3) are moving, then Ac4 (X4) could be completely free. Thefollowing relations exist: X=X1=X2=X3(=X4); Y1=Y2=Y3=Y4=0.

The same procedure applies to second orthogonal and coplanar axis (Y),FIG. 15. Back and forth translational motion along Y axis (Ty) isrealized by synchronized translational motions of all actuators alongspecified axis (t_(i2) , i=1, . . . , 4) and in the same direction.Supposing a linear displacement along Y axis of point A(Y), thesynchronized motions of all Actuation units (Ac_(i), i=1, . . . , 4)related with the Y axis must be activated and move in the same direction(Y=Y ₁=Y ₂=Y ₃=Y ₄); or at least three of them. That means, for example,if Ac₁ (Y₁), Ac₂(Y₂) and Ac₃(Y₃) are activated and moves; Ac₄(Y₄) can beinactivated: Y=Y ₁=Y ₂=Y ₃ (=Y ₄); X ₁=X ₂=X ₃=X ₄=0.

Vertical back and forth translational motions (Tz) of the table can beperformed by simultaneously concurrent motions of all actuation unit(Ac_(i), i=1, . . . , 4), FIG. 18 or at least three of them. Supposing Apoint displacement along Z axis (Z), then all the Actuation units (Ac)are activated, and pairs move together concurrently in oppositedirections towards the Z axis Z=tgα  X₁=tgαY ₂=tgαX ₃(=tgαY ₄) or thepoint (B)—the base center; or at least three of them (the correspondingforth one being inactivated). That means, for example, A_(c1)(−X ₁),Ac₂(−Y ₂) and Ac₃(X ₃) are activated and moves, and A₄(Y ₄) not.

Symmetric rotations around X or Y axis (Rx or Ry) are achieved bycombined back and forth linear motions (t _(i1(2)), i=1, 2) of a pair oftwo actuators Ac_(i) (i=1, 2), or at least one non-collinear with theaxis of rotation, FIGS. 14 and 16. In order to obtain a positive angulardisplacement α (β) simultaneously linear displacements actions inopposite directions along the correspondent orthogonal axis must beperformed. For example, for Rx(a) imposes A₂(−Y ₂) and/or A₄(−Y ₄) andfor Ry(β) imposes A₁(X ₁) and A₃(X ₃) to work for which α(β)=arctg(Z_(i)/a_(i)), where Z_(i)=X _(i)(Y _(i))arctg(α_(i)).

Symmetric rotations around the Z axis (Rz) are achieved by combined backand forth linear motions (t _(i12), i=1, . . . , 4) of the entire set offour actuators Ac _(i) (i=1, . . . , 4), or at least three of them, FIG.17. In order to obtain a positive angular displacement γ simultaneouslylinear displacement actions in the same direction around the Z axes mustbe performed. For example, for Rz(γ) imposes A ₁(−X ₁,Y ₂), A ₂(−X ₂,−Y₂) and A ₃(X ₃,−Y ₃) to work for which γ=arctg (Y _(i)/X _(i)).

As resulted from above, by choosing a number of four legs acting andsupporting points as a number in-between three points necessary forminimum stability and maximum six imposed for full motion capabilities,and by using compact bi-directional linear actuators, this parallelpositioning table is providing a trade-off, between an increasedaccuracy, speed and stability and dexterity, being able to deliver highpower, high-energy efficient 3D positioning trajectories.

The above Redundant Parallel Positioning Table (Rd-PPT) concept can beapplied for accurate, high speed, table-like automated or manuallydriven applications, as for example: alignment, simulation, machining,assembly, measurement, control, or testing or any other operations, frommechanical, optics, semiconductors (lithography, LCD, wafer, printing,etc.) processes in manufacturing, aviation, medical or bio-technologicalfields including their use in extreme environments (vacuum, cryogenic,magnetic, etc.).

The examples as described above provide a device and method toautomatically (or, manually) pose one body or several heavy bodies inspace with required precision, speed and stability. The positioningtable device is based on symmetric redundant six-degrees-of-freedomspatial parallel kinematic mechanism, a member of the Quadropods family.Each pod (leg) is built as a vertical supporting positioning moduleactuated by an in-parallel two-degrees-of-freedom motorized unit withmotors located at the base and supporting two non-motorized—theelevation and the guiding positioning units, respectively. The elevationunits consist of two opposite wedge systems arranged in pairs followingthe guiding positioning units from spherical bearings types. Throughtheir combined actions, a platform-like table can be easily andintuitively moved in linear and rotational Cartesian directions. Inorder to manipulate heavy loads as usually in synchrotron applicationsthey are, the device has the characteristics of compact size, lowprofile, and simple structure providing increased stiffness, precision,and speed positioning capabilities compared with prior art.

Further, the present invention provides fast and easy methods to adapt a6dof device to various changeable working conditions in thediffractometer environment.

The Redundant Parallel Positioning Table (Rd-PPT) device can be adaptedto work with fewer than 6dof (<6dof). The devices having 2dof, 3dof,4dof, or 5dof are derived from the general 6dof device with appropriatemodifications. These modifications provide devices with fewer than 6dofthat have similar performance and comparable capabilities, therebyproviding more options for sample/diffractometer positioning.

By modifying one or more of the active and/or passive joints from thebasic general structure 6-4-213 of FIG. 1 with similar joints havingrestricted functionalities, located on the first (I), second (II),and/or third (III) levels, as a) active joints—two (2) (2) dof with 2 ₁(1dof), b) passive joints—one (1) dof with 1₀, and c) three (3) dof with3₂ (2dof), 3₁ (1dof) or 3₀ (0dof) while ₀—null, ₁—one, ₂—two indices arethe effective dof permitted for a joint, different modified structures(Sm) can be obtained. Note that in the case of null (0) permittedmotions, the joint (and the entire level) can be eliminated.

The complete range of Sm structures includes twelve (12) members. Foreach of these, the redundancy (Rd) changes accordingly.

In the case of when the unmodified active joints (2) are substitutedwith constrained joints (21), the following structures a) 4-2 ₁13₂, 4-2₁13₁, 4-2 ₁13₀ (2 ₁1) based on 1dof passive joints and b) 4-2 ₁1₀3₂ (2₁3₂), 4-2 ₁1₀3₁ (2 ₁3₁), 4-2 ₁1₀3₀ (2 ₁) for constrained 1₀ substitutejoints are obtained based on the general 6-4-213 structure. Note thatonly one effective axis can be eliminated from an actuation point.

By substituting the passive 1dof joint (1) only with a constrained 1₀(blocked) joint, in the general case of 6-4-213, the followingstructures: 4-21₀3₂ (23₂), 4-21₀3₁ (23₁), 4-21₀3₀ (2) are of interest.

By substituting the 3dof joints only with constrained joints (3_(c))—3₂and 3₁ and 3₀, three Sm structures are obtained by substituting theminto the general/unconstrained joints mechanism (6-4-213): 4-213₂,4-213₁, and 4-213₀ (4-21).

Based on the general 6-4-(Pl)₂XS mechanisms (6dof) of FIG. 3 having(Pl)₂ generalized curvilinear planar joints/2dof, X-undefined 1dofjoint, S-spherical joint, a general specific modified mechanism (Mm) forless than 6dof (<6)-4-(Pl)_(i)X_(i)S_(k) can be defined. Here, i=1, j=0,k=0, 1, 2 indices represent the number of effective motions availablefor the constrained joints in a kinematic modified chain (K*) of amechanism.

By using the same type of joints (P and S) as in the 6dof/6-4-(2P)PSmechanism of FIG. 5, the following M_(m) mechanisms are found that havefewer dof: a) spatial—5-4-(2P)PS₂ (5dof/XYZRxRy), 4-4-(2P)PS₁(4dof/XYZRz), 3-4-(2P)PS₀/3-4-(2P)P (3dof/XYZ) and b) planar3-4-(2P)P₀S₁/3-4-(2P)S₁ (3dof/XYRz) and 2-4-(2P)P₀S₀/2-4-(2P) (2dof/XY);S₂ performs 2dof (Rx, Ry) and S₁(Rz) 1dof rotational motions only. Notethat, by the specificity of the mechanism, the Rz motion is alwaysrelated to X and/or Y motion (actuation), and Rx and/or Ry with Zmotion, respectively.

By using the active constrained joints_(2P)₁, working mechanisms withfewer dof are a) 3(XYZ)-4-(2P)₁PS₀ (3-4-(2P)₁P) and b) 2(XY)-4-(2P)₁P₀S₀(2-4-(2P)₁); P ₁ performs linear (1dof) motion in the actuation.However, in this case, at least four active (effective) axes must workand be concurrent in the same point (base center).

By using the same modular concept as in FIG. 7, including the base,table and positioning modules (Pm) for legs, the design concepts forfewer than 6dof can use all positioning units (Pu), FIG. 9, and theirarrangements FIGS. 11 and 12, as in the basic 6dof concept (Ac-active,El, Gu-passive) or, only some of them, through an adequate modifieddesign, e.g., 3 (XYZ)—4-(2P)P—(Gu), 3(XYRz)-4-(2P)S₁—(El). The last two(El and Gu) can be completely eliminated, as in 2(XY)-4-(2P).

The methodology to obtain the simple translational (Tx, Ty, Tz) and/orrotational motions (Rx, Ry, Rz) for any of the modified devices above,starting from the nominal position (X_(ij)=Y_(ij)=0, i=1, 2, 3, 4, j=1,2), is, in principle, the same and is derived from the 6dof device, asin FIGS. 13-18.

Thus, by using modified (constrained) dof of the two (P and S) types ofjoints only, several devices with fewer than 6dof have been produced inaddition to those with 6dof. However, by using all types of joints(e.g., R, RL, etc.), and different design concepts, different otherworking devices with fewer than 6dof can be obtained from the basic 6dofdevice, forming a complete family (213) of redundant parallelpositioning table devices.

Moreover, by modifying the actuation axes locations, as for example 123,the Quadropods' family of redundant parallel positioning table devicescan be enlarged with other members.

When the speed and dynamics of a device are not the main concern,positioning mechanisms having other structures with similar or improvedperformance can be employed. For example, the present Redundant ParallelPositioning Table (Rd-PPT) device can be adapted to work with increasedperformance regarding the manipulated sample (load). Such (Rd-PPT)mdevices are derived from the general 6dof device by applying suitablemodifications.

The present invention provides a device with 6dof that has features andscope similar to the device taught above but with increased performance,by which more options for sample/diffractometer load manipulation areprovided.

Specifically, the invention provides a solution for adapting the deviceto work in diffractometer environments with an increased load by bettertransfer of the force from the actuation to the table being moreuniformly dispersed inside the components, especially in performingvertical motions. Thus, a greater load can be manipulated without thedesign modifications as to increase the size (including stiffness) ofthe components (passive joints) by using the same actuation (power). Inother words, a smaller device can perform increased load manipulationwith the same passive components.

In this respect, one of the actuation axes of the active joints from thebasic structure (6-4-213) of FIG. 1 will become passive and in turn, thenext passive joint will become active. With this modification, the newlymodified 6-4-123 structure (Sm) has the active joint (2) on the secondlevel (II), being able to work with the same number and type of jointsas the basic 6dof device, but with another expected results regardingits positional behavior (load manipulation), FIG. 2. In fact, Sm isanother member of the larger family of redundant parallel kinematicstructures (1, 2, 3) described above. Note that the other members,6-4-231/6-4-321 and 6-4-132/6-4-312 are not of interest because, asnoted previously, the invention is limited to structures with activejoints on levels I and/or II, and spherical joints on level III.

On the basis of the generalized geometric model 6-4-(Pl)₂XS from FIG. 3,a generalized modified geometric model (Gm)_(m) 6-4-X(Pl)₂S is defined.Here, the (Pl)₂ joint on level II can generally perform any motions, butespecially inclined and horizontal and vertical planar motions (Σ_(P)),FIG. 4. The actuated and non-actuated type of joints can be freelychoosing from the actual existent portfolio. The A_(i) points are movingon generalized curves (C_(i)), i=i=1, . . . , 4 having each 2dof(l_(i)—curvilinear coordinate variable, see also FIG. 6) and relative tothe stationary base (C′_(i)), i=1, . . . , 4. Following this, theresultant pose—positions (XYZ) and orientation (ψ, φ, θ) values,respectively, of manipulated objects is dependent on: a) the actuationdisplacements (q ₁, i=1, . . . , 8) and b) geometrical (a_(i), b_(i),l_(i), d_(i), d′_(i), L, l, R, r) parameter values. Note that themodified structures (S)_(m) with fewer dof can be also obtained from thegeneral kinematic model of above by replacing one or more of the jointswith modified (restricted) motion. Then, the (general) geometric model(Gm)_(m) can be expressed as (<6)-4-X_(j)(Pl)_(i)S_(k) (i=1, 2; j=0, 1;k=0, 1, 2)

By using the same type of joints in a kinematic chain (K), as in the6-4-(2P)PS mechanism from FIG. 5, but with another arrangement, amodified mechanism Mm is defined as 6-4-P(2P)S, FIG. 6. Here (2P)represents an in-parallel planar actuation joint, performing horizontaland/or vertical (inclined) motions. These occur by making one of theactive axes of the planar joints (X or Y) and the passive, inclined (Zα)joint to be active. This can also be done in serial (stacked) mode. Bythis, 6 or fewer dof can be obtained from a synchronized combination ofall or fewer actuation axes, e.g., 3(XYZ) with 6-4-P(2P), 3dof (XYRz)with 6-4-P(2P)S, 2dof(X/YZ) with 6-4-2P. Note that for fewer dof, someof the joints can be eliminated, e.g., 3(XYZ)—S, 3dof(XYRz)—P(inclined),2dof(XY)—P(inclined) and S.

By using the same modular concept in the design, as exemplified in FIG.7, including the base, table and positioning modules (Pm) for legs,comprising the positioning units (Pu)—Ac(actuation), El (Elevation), Gu(Guiding) as in the basic concept, however with partially modifiedfunctionalities, a modified redundant parallel kinematic positioningdevice (Rd-PPT)_(m) can be produced, FIG. 8. This means that the firstaxes of the Ac positioning module become passive and the El (wedges)positioning module becomes active. This has a beneficial effect in thecase of electromechanically actuation (motors and ball screw) the devicebeing able to work with larger inclinations without forcing thehorizontal actuation bearing assembly, as a result of the wedge effect.Note that, in this case, the limited working angle of the wedges is morethan 30°.

As in the preferred embodiment of the present invention FIG. 9, aPositioning module (Pm) is a vertical stacked combination of three Pu,one active (Ac)—planar driven (Pu₁), and two inactive—El (Pu₂) and Gu(Pu₃), the first two as generally, compact parallelepiped blocks.However, in the modified design, the (Ac)_(m) having the first actuationaxes inactive (A11), and the second A12 axes still active, the Pu₂becoming active, and the detailed design has been adapted accordingly,FIG. 10. The inclined actuation is now acting closer to the table,stressing only the Gu components for up and down vertical motions. And,in the case of motor and ball screw actuation, the motors can be insideor outside, depending on the required aperture, FIGS. 11 and 12.

The methodology for obtaining the simple translational (Tx, Ty, Tz)and/or rotational motions (Rx, Ry, Rz) for the modified (Rd-PPT)_(m)device, starting from the nominal position (Xij=Yij)=0, i=1, 2, 3, 4,j=1, 2), remains in principle the same as that of the device of FIGS.13-18, however with the specific kinematic values, Tx (X=Xij, i=2, 4;j=2), Ty (Y=Yij, i=1, 3; j=2), Tz (Z=Zαi, i=1, . . . , 4; j=3). HigherTz(Z) displacements can be obtained by increasing the inclination angleof the wedge α>30°. And the available height of the working space willalso be enlarged. Note that the X/Y displacements again come from thebasic combination of Level I (and II) planar axes (active and passive).

By the modifications described above, some performance characteristicsof 213 mechanism are improved, and the Quadropods' family of redundantparallel positioning table devices is enlarged by a new member (123). Inaddition, by using adequate modified (constrained) joints, devices withfewer than 6dof can be obtained in order to complete the entireportfolio of possible Rd-PPT products.

Thus, it has been shown and described a redundant parallel positioningtable device. Since certain changes may be made in the presentdisclosure without departing from the scope of the present invention, itis intended that all matter described in the foregoing specification andshown in the accompanying drawings be interpreted as illustrative andnot in a limiting sense.

The invention claimed is:
 1. A redundant parallel positioning tabledevice Rd-PPT comprising: (a) a stationary base B; (b) a moving table Twith a fixing surface ΣT on which a sample Sp can be mounted; and (c) atleast one set of four supporting legs, one being redundant,symmetrically arranged around the center of the base in opposed pairs,each leg having a base end connected to the stationary base and a tableend connected to the moving table; (d) each leg being a 123 kinematicchain structure (K) such that the device provides a maximum of sixdegrees of freedom.
 2. The redundant parallel positioning table deviceof claim 1 wherein the parallel positioning table device is modular withthe supporting legs as positioning modules Pm, the positioning modulesbeing parallel to each other, vertical with respect to one axis ofsymmetry (Z), and orthogonal with respect to a second axis of symmetry(X or Y), as active two-degree-of-freedom pillars.
 3. The redundantparallel positioning table device Rd-PPT of claim 2 wherein thepositioning modules are located symmetrically and in opposed pairs abouta central location of the stationary base B.
 4. The redundant parallelpositioning table device Rd-PPT of claim 2 wherein each of thepositioning modules comprises a stacked combination of a passiveelevation positioning unit El, an active planar positioning unit Ac, anda passive spherical guiding positioning unit Gu.
 5. The redundantparallel positioning table device Rd-PPT of claim 4 wherein the planarpositioning unit Ac includes an inclined surface base fixed to a linearguided prismatic first wedge, a mover M fixed on a second wedge movablerelative to the inclined surface base in two orthogonal axes, a linearactuator moving the mover M in the first orthogonal axis, a linear guideactuator moving the mover M in the second orthogonal axis, a redundantlinear actuator moving the mover M in the first orthogonal axis, and aredundant linear guide actuator moving the mover M in the secondorthogonal axis.
 6. The redundant parallel positioning table deviceRd-PPT of claim 5 wherein the first orthogonal axis of each of a firstopposing pair are parallel to each other and the second orthogonal axisof each of the first opposing pair are parallel to each other, and thefirst orthogonal axis of each of a second opposing pair are parallel toeach other and the second orthogonal axis of each of the second opposingpair are parallel to each other, forming an inclined (pyramidal) eightaxis actuation module.
 7. The redundant parallel positioning tabledevice Rd-PPT of claim 4 wherein the elevation positioning unit Elcomprises a pair of movable wedges relative to each other wherein thelower wedge is a linear guided positioning unit on V-type guidedsurfaces and the upper wedge supports the spherical guiding positioningunit Gu, wherein the inclined moving surfaces of an opposed pair of legsforms a V shaped assembly.
 8. The redundant parallel positioning tabledevice Rd-PPT of claim 4 wherein the passive spherical guidingpositioning unit Gu is a spherical joint S with a truncated conicalpillar mounted on the elevation positioning unit El, a sphere attachedto the pillar and having convex surface, and a two-part housing havingan adjustable concave surface slidable on the convex surface, bothhousing parts being connected to the bottom side of the moving table. 9.A redundant parallel positioning table device Rd-PPT comprising: (a)stationary base B; (b) moving table T with a fixing surface ΣT on whicha sample Sp can be mounted; and (c) at least one set of four supportinglegs, one being redundant, symmetrically arranged around the center ofthe base and in opposed pairs, each leg having a base end connected tothe stationary base and a table end connected to the moving table; (d)each leg being a 123 kinematic chain structure (K) such that at leastone axis of the joints of at least one level is constrained, therebyproviding fewer than six degrees of freedom.